1. Field of the Invention
This invention relates to the field of communication. More specifically, the invention relates to communication networks.
2. Background of the Invention
Although ATM is able to carry different types of traffic, certain features that are applied to the ATM permanent virtual circuit (PVC) that is carrying the traffic cannot be applied to the different types of traffic. An organization may wish to apply features, such as ACLs, counters, rate limiting, etc., to different types of traffic from the perspective that the different types of traffic are different traffic flows. In addition, an organization may wish to transparently switch one type of traffic while routing another type of traffic. This would allow the organization to provide value added services for the routed traffic. Unfortunately, the different traffic flows are represented as a single PVC.
Routers typically internally represent each connection (whether it be an IP route, a label switched path, etc.) as an interface or set of interfaces, which is a network layer entity. Since an interface is a network layer entity, it includes various pieces of information needed for the network layer.
FIG. 1 (Prior Art) is a diagram illustrating an exemplary data structure for an interface. An interface structure 101 includes multiple fields describing the interface. An interface ID field 103 indicates a value identifying the interface. An interface type field 105 describes the type of interface (e.g., Ethernet, ATM, PoS, etc.). An IP address field 107 identifies a 32-bit IP address corresponding to the interface. A secondary IP address field 109 indicates a second 32-bit IP address for the interface. A maximum transmission unit (MTU) field 111 indicates the maximum allowable packet size to be transmitted with the interface. A bandwidth field 113 indicates the amount of bandwidth allocated to the interface. The interface structure 101 is a relatively expensive structure.
The relatively expensive interface structure consumes memory of a network element and consumes bus resources when the network element transfers interface structures to its line cards. In addition, the interface structure is a layer 3 entity that is not utilized by lower layers.